Fix a leak when copying a STATIC COW SV to a stringified SV

This is minor a a regression introduced by commit 914bb57489325d34:
    Define a third kind of COW state; STATIC

    ...

    sv_setsv_flags() and sv_setsv_cow() will preserve this state

There was a small omission in the copy code - it didn't handle the case where
the destination SV owned a string buffer already. This is actually
relatively rare - triggering it requires a scalar in code path that is
assigned both strings and booleans. Minimal test case is:

    my $got = 1;
    $got .= "";
    $got = ref "";

cut down from &is in t/comp/parser.t

0 files changed, 0 insertions, 0 deletions